We saw many different kinds of rock on our trip, and I’ve been trying to make sense of it all. In particular, the area known as the Colorado Plateau has a beautiful display of layered rock strata, all organized from oldest to youngest. The Colorado Plateau covers an area of 130,000 square miles in western Colorado, southeastern Utah, northwestern New Mexico, and northern Arizona.
Ancient Precambrian (greater than 570 million years old) rocks are visible only in the deepest canyons, such as the Grand Canyon. They are mostly metamorphic rocks formed deep in the earth.
During the Paleozoic Era (570-245 million years ago, mya), the region was periodically covered by ocean. Thick layers of sediments were laid down on the shallow ocean floor. When the seas retreated, silt from streams and sand was deposited or older layers were removed by erosion.
During the Mesozoic Era (245-66 million years ago, the age of the dinosaurs), terrestrial deposits from sand dunes and volcanic ash dominate the rock layers, but there are also sediments from short-lived bodies of water.
About 20 million years ago, movement of tectonic plates caused the elevation of region by more than a mile, forming the Colorado plateau. Starting around 6 million years ago, the Colorado River began to carve the Grand Canyon, exposing the multicolored rock layers.
The various parks have rocks from different eras:
Grand Canyon: 1840 mya-270mya, you won’t find dinosaur fossils here, as the rocks are too old.
Zion: 270mya-120 mya
Capitol Reef: 290mya-65mya
Dinosaur: 2320mya-present (at least that’s what they claimed)
You may notice that the youngest rocks in the Grand Canyon are the oldest rocks at Zion. The Colorado Plateau forms the Grand Staircase, with a gradient of rocks of different ages. Oldest rocks are exposed in the south, younger rocks to the north.
http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/Grandstair.html
Roz and Dan on the road 